Efforts to tune the bulk physical properties of concrete are hindered by a lack of knowledge related to the atomic-level structure and growth of calcium silicate hydrate phases, which form about 50–60% by volume of cement paste. Here we describe the first synthesis of compositionally uniform calcium silicate hydrate phases with Ca:Si ratios tunable between 1.0 and 2.0. The calcium silicate hydrate synthesized here does not contain a secondary Ca(OH)2 phase, even in samples with Ca:Si ratios above 1.6, which is unprecedented for synthetic calcium silicate hydrate systems. We then solve the atomic-level three-dimensional structure of these materials using dynamic nuclear polarization enhanced 1H and 29Si nuclear magnetic resonance experiments in combination with atomistic simulations and density functional theory chemical shift calculations. We discover that bridging interlayer calcium ions are the defining structural characteristic of single-phase cementitious calcium silicate hydrate, inducing the strong hydrogen bonding that is responsible for stabilizing the structure at high Ca:Si ratios.
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Atomic-level motion may drive bacteria's ability to evade immune system defenses, finds IU study - IU Newsroom
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IU Newsroom
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Atomic-level motion may drive bacteria's ability to evade immune system defenses, finds IU study
IU Newsroom
Through the use of nuclear magnetic resonance spectroscopy, he and colleagues measured the movement of atoms in CzrA and identified those most affected by zinc. They then "swapped" these atoms out with different amino acids and found that the protein ...
and more &raquo;
Atomic-level motion may drive...

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05-16-2017 10:27 PM

Atomic-level motion may drive bacteria's ability to evade immune system defenses - Science Daily
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Science Daily
<img alt="" height="1" width="1">
Atomic-level motion may drive bacteria's ability to evade immune system defenses
Science Daily
Through the use of nuclear magnetic resonance spectroscopy, he and colleagues measured the movement of atoms in CzrA and identified those most affected by zinc. They then "swapped" these atoms out with different amino acids and found that the protein ...
and more &raquo;
Atomic-level motion may drive bacteria's...